The Abbasid dynasty, or Abbasids, was an Arab dynasty that ruled the third Islamic caliphate between 750 and 1258. They were from the Qurayshi Hashimid clan of Banu Abbas, descended from Abbas ibn Abd al-Muttalib. The Abbasid Caliphate is divided into three main periods: Early Abbasid era (750–861), Middle Abbasid era (861–936) and Later Abbasid era (936–1258). A cadet branch of the dynasty also ruled as ceremonial rulers for the Mamluk Sultanate (1261–1517) until their conquest by the Ottoman Empire.